Vertical integrated PtSe2/4H-SiC vdW heterojunction for ultra-sensitive UV imaging and flame detection.

High-performance ultraviolet (UV) photodetectors are critically needed for a wide range of applications. However, simultaneously achieving high sensitivity and fast response speed remains a significant challenge. In this work, we demonstrate the fabrication of a vertical PtSe₂/4H-SiC van der Waals heterostructure (vdWH) photodiode with an ultrathin AlO_x interfacial passivation layer for UV detection. The synergistic combination of the high carrier mobility of 2D PtSe₂ and the strong UV absorption of 4H-SiC, along with the suppressed interface recombination and enhanced carrier collection, enables ultrasensitive and ultrafast self-powered UV detection. Moreover, the applications of PtSe₂/4H-SiC device in UV imaging and flame detection are successfully demonstrated, highlighting its potential for next-generation UV optoelectronic devices and systems in biomedical diagnostics, space communications, and environmental monitoring.